JAXA-GCF project - high-quality protein crystals grown under microgravity environment for better understanding of protein structure

Since 2003, Japan Aerospace Exploration Agency (JAXA, former NASDA) has been conducting a project on a semi-annual basis (JAXA-GCF) to obtain high-quality protein crystals in the microgravity environment using the Russian transportation system. For this project, protein samples were mostly provided by Japanese users for whom JAXA provided technical and clerical support for crystallization experiments in microgravity. For the project, JAXA has constructed a user-friendly support service for microgravity experiments and provided regular and frequent flight opportunities. To simplify and improve technological matters, JAXA devised a gel-tube method crystallization device, which is effective both in space and on ground, based on the counter-diffusion technique. JAXA also provided ground-based techniques for efficient preliminary optimization of crystallization conditions using a 1-dimensional simulation and for harvesting and cryoprotecting crystals before X-ray diffraction experiments. These improvements have significantly increased the success rate of obtaining useful results. In conclusion, JAXA has developed technologies for growing, in microgravity, high-quality protein crystals, which may diffract up to atomic resolution, for a better understanding of 3-dimensional protein structures through X-ray diffraction experiments.     

Axial and radial fluorescence of dye-doped polymer fiber

Fluorescence spectra of perylene-doped polymer fiber were measured in both radial and axial directions, i.e., for leaky and guided beams, by exciting the fiber with a pulsed laser of 460-540-nm wavelength. Green (540-550 nm) and yellow (580 nm) peaks were observed in the radial fluorescence spectrum. Measuring fluorescence change at positions closer to the input end and progressing forward to the output end, we observed that green fluorescence decreased rapidly corresponding to an attenuation constant at incident laser wavelength. In contrast, yellow fluorescence decreased gradually, because it was induced by the absorption of green fluorescence, which attenuated more gradually than incident laser. Therefore, in axial output beams, green fluorescence was much weaker than yellow. As incident laser power increased, intensities of axial green fluorescence and radial fluorescence (both green and yellow) saturated to a certain level. In contrast, axial yellow fluorescence increased nonlinearly with increase in laser power. The output light intensity became strongest at a fiber length of 20-30 mm. These phenomena were analyzed theoretically taking self-absorption and stimulated emission by fluorescent dyes into consideration     

Highly robust ultrathin silicon nitride films grown atlow-temperature by microwave-excitation high-density plasma for gigascale integration

This paper focuses attention on electrical properties of ultra-thin silicon nitride films grown by radial line slot antenna high-density plasma system at a temperature of 400°C as an advanced gate dielectric film. The results show low density of interface trap and bulk charge, lower leakage current than jet vapor deposition silicon nitride and thermally grown silicon oxide with same equivalent oxide thickness. Furthermore, they represent high breakdown field intensity, almost no stress-induced leakage current, very little trap generation even in high-field stress, and excellent resistance to boron penetration and oxidation     

Ambient dose equivalent conversion coefficients for radionuclides exponentially distributed in the ground

Conversion coefficients of radionuclide deposition density to the ambient dose equivalent rate at 1 m height above ground were calculated for exponentially distributed sources in the ground. First, Monte Carlo transport simulations assuming exponential distributions in the ground were performed to obtain ambient dose equivalent for mono-energetic gamma-ray sources having different relaxation depths; next, on the basis of the simulated data, conversion coefficients for radionuclides were composed considering recent nuclear decay data. The ambient dose equivalent rates were then compared to the effective dose rates for reference adults and a new-born baby as well as to air kerma rates quoted from previous studies. It was confirmed that the ambient dose equivalent sufficiently overestimates effective doses, independently of age, for sources exponentially distributed in the ground. Furthermore, the air kerma was found to also overestimate the effective doses for all ages in the same conditions. In order to verify the computed conversion coefficients, the ratio of ambient dose equivalent to air kerma obtained by simulation was compared to the ratios measured at hundreds of locations in Japan which have been contaminated with radioactive cesium after the accident at the nuclear power plant in Fukushima Prefecture, Japan, in 2011; a good agreement was observed.     

Evaluation of MC3T3-E1 Cell Osteogenesis in Different Cell Culture Media

Many biomaterials have been evaluated using cultured cells. In particular, osteoblast-like cells are often used to evaluate the osteocompatibility, hard-tissue-regeneration, osteoconductive, and osteoinductive characteristics of biomaterials. However, the evaluation of biomaterial osteogenesis-inducing capacity using osteoblast-like cells is not standardized; instead, it is performed under laboratory-specific culture conditions with different culture media. However, the effect of different media conditions on bone formation has not been investigated. Here, we aimed to evaluate the osteogenesis of MC3T3-E1 cells, one of the most commonly used osteoblast-like cell lines for osteogenesis evaluation, and assayed cell proliferation, alkaline phosphatase activity, expression of osteoblast markers, and calcification under varying culture media conditions. Furthermore, the various media conditions were tested in uncoated plates and plates coated with collagen type I and poly-L-lysine, highly biocompatible molecules commonly used as pseudobiomaterials. We found that the type of base medium, the presence or absence of vitamin C, and the freshness of the medium may affect biomaterial regeneration. We posit that an in vitro model that recapitulates in vivo bone formation should be established before evaluating biomaterials.     

Equation of purity for crystals produced from a cmsmpr crystallizer

Literature data of the amount of liquid contained per crystal w L ( L ) measured for various chemicals are correlated only with the crystal size L as: w L ( L ) L 4 . Using the empirical equation, an equation of purity P for crystals produced from a continuous mixed-suspension, mixed-product-removal (CMSMPR) crystallizer at steady state is successfully derived as: P = 100 \times \left( 1 - {4k \cdot G \cdot \tau \over \rho_{\rm C} \cdot k_{\rm v} + 4k \cdot G \cdot \tau} \right).     

Plasmons in nanoscale and atomic-scale systems

Plasmons in metallic nanomaterials exhibit very strong size and shape effects, and thus have recently gained considerable attention in nanotechnology, information technology, and life science. In this review, we overview the fundamental properties of plasmons in materials with various dimensionalities and discuss the optical functional properties of localized plasmon polaritons in nanometer-scale to atomic-scale objects. First, the pioneering works on plasmons by electron energy loss spectroscopy are briefly surveyed. Then, we discuss the effects of atomistic charge dynamics on the dispersion relation of propagating plasmon modes, such as those for planar crystal surface, atomic sheets and straight atomic wires. Finally, standing-wave plasmons, or antenna resonances of plasmon polariton, of some widely used nanometer-scale structures and atomic-scale wires (the smallest possible plasmonic building blocks) are exemplified along with their applications.